Lactating breast infection

Mastitis, when associated with lactation is known as lactational mastitis or puerperal mastitis (1). It can be:

• non infectious mastitis – is seen when the accumulated milk causes an inflammatory response
• infectious mastitis – occurs when unresolved milk stasis leads to an overcome of the anti infective protection provided by the immune factors in milk resulting in bacterial overgrowth
• sub clinical mastitis – is seen when indicators of an inflammatory response (e.g. - interleukin – 8) are present despite the absence of clinical signs of mastitis.
  • commonly seen amongst women in Bangladesh, Tanzania, Malawi and South Africa
  • is associated with inadequate milk removal and poor weight gain in infants
  • in HIV positive mothers, there is a higher rate of mother to child transmission of HIV since sub clinical mastitis is associated with an increase HIV load in breast milk (1)

There is cellulitis of the interlobular connective tissue within the breast (2).

Breast feeding may cause abrasion of the skin around the breast and, on occasion, cracking of the nipple. This permits the entry of infective organisms, most commonly Staphylococcus aureus but also Staphylococcus epidermidis and streptococci. This may result in a circumareolar breast abscess, or deep infection of the lactiferous ducts.

Uncommonly, infections arise in the sebaceous glands (of Montgomery) of the areola, where they resemble skin boils.

Close to half of all cases of mastitis is seen during the first four weeks after starting breast feeding although it may occur at any stage during lactation or when the number of feeds (or milk expression) are reduced (3).

• lactational mastitis affects approximately 2% to 20% of people who are breastfeeding and is defined by inflammation of the mammary gland (4)
  • symptoms and findings include pain, erythema, induration, and swelling

Reference:

• (1) World Health Organization (WHO) 2000. Mastitis: Causes and Management
• (2) The National Collaborating Centre for Primary Care (NCCPC) 2006. Postnatal care: Routine postnatal care of women and their babies
• (3) Guidelines and Audit Implementation Network (GAIN) 2009. Guidelines on the treatment, management & prevention of mastitis
• (4) Louis-Jacques AF, Berwick M, Mitchell KB. Risk Factors, Symptoms, and Treatment of Lactational Mastitis. JAMA. Published online January 26, 2023. doi:10.1001/jama.2023.0004